It seems like a simple enough brief, (at least in its goals) “Create the most beautiful and vivid display on a tablet.” And initially it was. With Sony’s TV technology we knew we could create colour ranges that weren’t possible otherwise and with the amazing foundations laid down by the team behind Xperia Z2 Tablet’s display we had made huge steps forward in terms of delivering on brightness / vivid colours.
However, that’s where simplicity ends.
Let’s take the statement – “beautiful and vivid” as a starting point. Beauty is a human construct, it’s as much about psychology as it is about any kind of engineering challenge, and whilst there is an engineering consensus on what “vivid” means, it’s almost as reliant on context as “beauty” is. It’s easy to create a vivid colour in a darkened room but the same display could look totally different under direct sunlight.
People remember different colours in different ways – emotionally charged memories often lead to more saturated colours when they are recalled, and there are some colours that particularly stand out – deep reds for example are what we’d call a “memory colour”. It was important therefore that we were able to produce this “intensifying” effect, but equally important that we didn’t apply it across the board. Natural colours like human skin stand out like a sore thumb if you crank up the saturation.
Ironically a lot of the challenges for creating deep natural colours relate to how you create white light. Traditional LED displays combine certain wavelengths of blue and yellow light by shining a blue LED through yellow phosphor. This more or less works in most situations, but when really fine control is necessary, it starts to become a limiting factor. That’s why Sony came up with its “Live Colour LED” technology – this uses a blue LED but shines it through polarised red and green phosphor so that the display has, in essence RGB control over every single LED in the array. In human-speak that means we get unrivalled control over the colours we produce and can make them as natural or intense as we need to.
The next challenge was all about vividness and once all the colour technology was in place the main issue was how we make that experience uniform regardless of the ambient light. For the first time in Xperia Z4 Tablet we rolled out technology that allows us to change individual pixels within the display based on the ambient light around the device. So, for example we’re able to keep blacks black but brighten up whites when the device is in bright sunlight. This is a huge step forward compared with what has been available before – we could compensate for ambient light, but it was on an all-or-nothing basis. The new technology produces a really dramatic improvement.
But, and it’s a huge “but”, none of this makes any difference if the new technology is the size of a house and drinks battery. Every time we create something new, we have to think about how it will affect our devices battery performance and it’s a testament to people involved that we were able to achieve all of the improvements I’ve talked about here and to still deliver a display that uses 40% less power than before and weighs 20 grams less. Each of the technologies I’ve already talked about was designed from the ground up with battery saving in mind. Take for example the Live Colour LEDs – they’re an incredibly efficient way of creating light.
The point of all this though is quite simple. The way that a person feels about their tablet will be dictated by the experiences that they have with it. The display has a huge effect on this experience, it determines how movies and images affect people, it’s the primary way of interacting with the tablet and – as new technologies come to light – we look forward to making these experiences even more immersive.